Train Delay and Railway Line Capacity Under Combinations of Structured and Flexible Operations

UIUC Project Information


NuRail Project IDNURail2014-UIUC-R16
Project TitleTrain Delay and Railway Line Capacity Under Combinations of Structured and Flexible Operations
UniversityUniversity of Illinois at Urbana-Champaign
Project ManagerTyler Dick
Principal InvestigatorTyler Dick
PI Contact Information
Funding Source(s) and Amounts Provided (by each agency or organization)$0 NURail, $100,000 cost share
Total Project Cost$
Agency ID or Contract NumberDTRT13-G-UTC52 (Grant 2)
Start Date2016-08-16
End Date2018-08-15
Location
Brief Description of Research ProjectMany rail corridors are experiencing a transition from bulk freight trains operating on flexible schedules that maximize efficiency and economies of scale, to passenger, commuter and premium intermodal services that require more structured operations with fixed arrival and departure times. Although these premium trains receive higher priority, maintaining the schedule flexibility of bulk freight trains while simultaneously providing the precision and level of service required by passenger and intermodal trains presents a substantial operational challenge on the predominantly single-track North American rail network. The objective of this research is to investigate the behavior of routes with combinations of trains exhibiting differing amounts of terminal departure time variability, ranging from precise schedules to complete flexibility. This research seeks to characterize the relationship between the mixture of scheduled and flexible trains operating on a rail corridor, the amount of schedule flexibility in the train departure and running times, and the level of service (train delay) experienced by each of the different types of trains. This research is conducted via simulation of a representative North American single-track corridor with Rail Traffic Controller (RTC) software. RTC is used to quantify the delay caused by the various mixtures of structured and flexible trains on the corridor. To serve as a baseline condition for a given train volume and single-track infrastructure layout, a structured cyclic train schedule is developed that minimizes delay under structured (entirely scheduled) operations. Simulation scenarios are then created by incrementally replacing scheduled trains with trains on flexible schedules to quantify the train delay response. The experiment design also considers various relative levels of schedule flexibility for each combination of scheduled and flexible trains (or “traffic mixture”), traffic volume and amount of second track to evaluate both train delay and line capacity under different operating realms.
Describe Implementation of Research Outcomes (or why not implemented)The proposed research project will be divided into several tasks to isolate different factors and their relationships to train delay and line capacity. The scope of later tasks may be refined as the results of earlier tasks reveal interesting relationships to be investigated further. All project tasks will be completed by a student Graduate Research Assistant.
Task 1: Uniform Schedule Flexibility and Infrastructure Investment
This research task investigates the trade-off between the amount of schedule flexibility on a route and the infrastructure required to maintain a given level of service for a fixed amount of traffic. Train operations will be simulated on two representative single-track routes with RTC software. All trains on the route will be of the same type with identical power, weight, length, priority and level-of-service characteristics. A baseline minimum-delay schedule will be developed for each route under an initial infrastructure. The experiment design introduces schedule flexibility and infrastructure expansion (new passing sidings and sections of second main track) to examine the interaction between these factors and the train delay response. A uniform amount of schedule flexibility is applied to all trains in generating the random train schedules for each simulation scenario of the experiment design. It is hypothesized that increasing schedule flexibility will require additional infrastructure investment to maintain level of service for constant train volumes.
Task 2: Train-Type Delay for Combinations of Structured and Flexible Operations
In Task 2, a factorial experiment will be designed to determine the relationship between the proportion of scheduled and flexible trains within a given traffic volume, relative level of schedule flexibility for the flexible trains and the train delay response for scheduled and flexible trains. The traffic volume and route infrastructure will be kept constant. Starting with the initial structured schedule developed for Task 1, schedule flexibility will be introduced to a certain fraction of the trains within the RTC simulation. All flexible trains will have the same amount of schedule flexibility for each simulation scenario. The resulting train delays will illustrate the behavior of routes with mixed and flexible train operations compared to routes that are completely structured or completely scheduled. The results will also indicate if the introduction of flexible trains will have a greater impact on the delay of the scheduled or flexible trains, and how this impact grows and/or changes as schedule flexibility is increased.
Task 3: Equivalent Capacity of Combinations of Structured and Flexible Operations
In Task 3, the experiment in Task 2 will be repeated for different traffic volumes. The resulting train delays will allow for examination of the capacity trade-off between traffic volume and mixture of scheduled and flexible trains operating on a route. For example, it is hypothesized that a higher traffic volume with fewer flexible trains may exhibit the same average train delay as a scenario with a lower traffic volume but a greater proportion of flexible trains. In this case the difference in traffic volume would represent the “capacity penalty” of allowing some trains to operate on flexible schedules.
Task 4: Benefits of Infrastructure Expansion under Combinations of Structured and Flexible Operations
Task 4 will build upon the simulations conducted for Task 3 by introducing additional infrastructure to mitigate the increased delays from additional traffic volume, additional schedule flexibility and (as hypothesized) greater fraction of flexible trains. The Task 2 and 3 operating scenarios will be re-simulated on the expanded track infrastructure in RTC to determine if there are differences in the train delay benefits to scheduled and flexible trains. This task will also investigate the sensitivity of train delay reduction to the exact location of infrastructure expansion projects under different combinations of scheduled and flexible trains (structured and flexible operations).
The deliverable for this project will be a final report documenting the above tasks. Each individual research task will be developed into a journal paper.
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Final Report